President-elect Donald Trump’s choice of Exxon Mobil CEO Rex Tillerson to lead the State Department would be unsettling at any time. It’s not just that he would go into one of the administration’s most challenging jobs without any government experience, or that the head of the lead agency in international climate negotiations would be coming from the fossil fuels industry.

It’s his cozy relationship with Russia and its autocratic leader Vladimir Putin, with his aggressive and destabilizing behavior in the world, that is raising serious concerns with Democrats and Republicans alike.

The timing could not be more disturbing, with the announcement of Tillerson’s selection coming just one day after House and Senate Republican leaders agreed to follow-up investigations on the CIA’s conclusion that Russia was involved in the hacking of Democratic Party computers in an effort to assist Trump’s candidacy.

Russia has been troublesome to U.S. interests in significant other ways: its invasion of Ukraine and annexing of Crimea, its air strikes and other meddling in Syria; its provocative moves around U.S. and British military assets in the air and on the high seas. As Senate Majority Leader Mitch McConnell so aptly put it to reporters, “The Russians are not our friends.”

They are, however, friends with Rex Tillerson.

In 2013, Putin honored Tillerson with the Order of Friendship for his work “strengthening cooperation in the energy sector.”

Tillerson will have plenty of explaining to do when he appears before the Senate Foreign Relations Committee in the confirmation process next month. He will need to answer for his criticisms of sanctions against Russia that stopped some of Exxon Mobil’s ventures there. He will need to convince senators, and the American public, that he can separate the business ambitions that drove his courtship with Russia from the greater national interest in dealing firmly with a ruthless regime. “I don’t see how anybody can be a friend of this old-time KGB agent,” Sen. John McCain, R-Ariz., said of Putin.

Democrats will look at Tillerson’s corporate history and ask tough questions about his commitment to climate action and human rights.